This is a note to let you know that I've just added the patch titled
swap: fix swapfile read/write offset
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
swap-fix-swapfile-read-write-offset.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From caf6912f3f4af7232340d500a4a2008f81b93f14 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Tue, 2 Mar 2021 14:53:21 -0700
Subject: swap: fix swapfile read/write offset
From: Jens Axboe <axboe@xxxxxxxxx>
commit caf6912f3f4af7232340d500a4a2008f81b93f14 upstream.
We're not factoring in the start of the file for where to write and
read the swapfile, which leads to very unfortunate side effects of
writing where we should not be...
[This issue only affects swapfiles on filesystems on top of blockdevs
that implement rw_page ops (brd, zram, btt, pmem), and not on top of any
other block devices, in contrast to the upstream commit fix.]
Fixes: 48d15436fde6 ("mm: remove get_swap_bio")
Fixes: dd6bd0d9c7db ("swap: use bdev_read_page() / bdev_write_page()")
Cc: stable@xxxxxxxxxxxxxxx # 4.4
Signed-off-by: Anthony Iliopoulos <ailiop@xxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/page_io.c | 11 +++--------
mm/swapfile.c | 2 +-
2 files changed, 4 insertions(+), 9 deletions(-)
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -32,7 +32,6 @@ static struct bio *get_swap_bio(gfp_t gf
bio = bio_alloc(gfp_flags, 1);
if (bio) {
bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);
- bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
bio->bi_end_io = end_io;
bio_add_page(bio, page, PAGE_SIZE, 0);
@@ -244,11 +243,6 @@ out:
return ret;
}
-static sector_t swap_page_sector(struct page *page)
-{
- return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
-}
-
int __swap_writepage(struct page *page, struct writeback_control *wbc,
bio_end_io_t end_write_func)
{
@@ -297,7 +291,8 @@ int __swap_writepage(struct page *page,
return ret;
}
- ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
+ ret = bdev_write_page(sis->bdev, map_swap_page(page, &sis->bdev),
+ page, wbc);
if (!ret) {
count_vm_event(PSWPOUT);
return 0;
@@ -345,7 +340,7 @@ int swap_readpage(struct page *page)
return ret;
}
- ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
+ ret = bdev_read_page(sis->bdev, map_swap_page(page, &sis->bdev), page);
if (!ret) {
count_vm_event(PSWPIN);
return 0;
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1653,7 +1653,7 @@ sector_t map_swap_page(struct page *page
{
swp_entry_t entry;
entry.val = page_private(page);
- return map_swap_entry(entry, bdev);
+ return map_swap_entry(entry, bdev) << (PAGE_SHIFT - 9);
}
/*
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-4.4/swap-fix-swapfile-read-write-offset.patch
